A next-generation mobile communications system includes various wireless networks, and each of radio access technologies is distinctive in such aspects as capacity, coverage, data rate and mobility support capability. Novel radio access technologies emerge one after another. These radio access technologies complement each other, and are converged and integrated with each other.
In the prior art, when a terminal detects a proper wireless fidelity (WiFi) access point (AP), the terminal disconnects from a 3G (3rd Generation) network, and automatically switches to a WiFi network for service transmission; when the terminal does not detect a WiFi network, the terminal automatically switches back to the 3G network. However, this method has low resource utilization of a wireless communications network.